The treatment of textile materials with various chemicals, dyestuffs, resins and the like has been long carried out using aqueous baths in these processes. In such processes the fabric is essentially saturated by immersion in a water bath containing the treating chemical and eventually the water must be removed in order to continue the processing or to dry the fabric. Of the many procedures employed in the past for the treatment of fabrics, the most commonly employed is the pad-dry process in which the fabric is immersed and saturated with the aqueous treating solution, squeezed between rollers to a given wet pick-up and subsequently dried or dried and cured on a frame or heated drying roll before being taken up in a roll once again. The amount of water retained by the fabric is normally controlled by the pressure of the squeeze roll; in conventional methods a lower limit of about 50 to 70 percent water based on the weight of the fabric is still retained, depending upon the particular fabric used. This large amount of water requires a tremendous amount of energy in the form of heat to dry the fabric. It has been estimated that the amount of energy required to remove the water and dry the fabric is many times greater than the amount of energy that is needed in heating the cloth to carry out the desired chemical treating step, as for example, in the application and cure of a wash and wear finish on the fabric, or in the continuous dyeing of a fabric. In addition to the pad-dry process, in which the water is removed by squeezing between rollers, other procedures have recently been developed for more efficient removal of water. In one such procedure the saturated fabric is conveyed to a jet squeezer which employs a stream of compressed air jetting outward at the point of contact between the fabric and the nip rolls to substantially reduce the moisture content of the fabric. The use of this technique has resulted in a decrease of the water content in the fabric to about half of that normally remaining when using the squeeze roll technique discussed above. In another procedure vacuum extractor rolls are used. This process entails conveying the wet fabric as it exits from the treating bath over a perforated roll within which a vacuum is created whereby the moisture is extracted from the fabric. In some instances, roller coating methods can be used with continuously deliver aqueous treating composition to the fabric, with the add-on governed by the fabric speed and the rate of delivery of the treating composition by the coating roller. In this procedure the treating composition generally remains predominately on or near the surface of the fabric, particularly when low add-ons are involved.
Within the past few years, several new approaches have been taken to obtain uniform application of compositions to porous substrates. These recently developed procedures use foams in different form. However, the methods by which the foams had been applied to treat the fabric or yarn leave much to be desired. One such disclosure is to be found in U.S. Pat. No. 3,697,314, issued Oct. 10, 1972. In this patent there is shown a method for producing foam and then passing a yarn through the foam so as to coat the exterior surface of the yarn with the foamed treating agent. It stresses that the yarn must pass through the foam agglomeration in order to assure a uniform distribution of the agent over the entire circumferential surface of the yarn as it passes through the foam and shows no means by which the foam could be applied on only one surface of a fabric or material and still obtain uniform distribution or uniform penetration of the interior of the yarn or fabric. An earlier attempt to use foam for the treatment of textile materials is to be found in U.S. Pat. No. 1,948,568, issued Feb. 27, 1934. In this disclosure, a textile material is suspended in a closed container and foam is pumped into the container and forced through the textile material until the textile material is uniformly impregnated from all sides throughout the substrate structure and saturated with the textile treating agent in the form of a foam. In the batch process disclosed in this patent, the textile material is in a stationary or fixed position.
Though a few disclosures do exist on the use of foam for the treatment of textile materials, essentially all of the industry still uses aqueous treating baths and processes in which the fabrics are generally immersed in the liquid bath for the application of the treating material or the liquid itself is applied by means of a kiss roll to the textile. As previously indicated, this entails the use of a large amount of energy to subsequently remove the water from the fabric.